Lunar Prospector

Moon Water Remains a Mystery -- The July 31, 1999 crash of Lunar Prospector
into the Moon did not liberate detectable signs of water, say scientists.
The possibility of water-ice in shadowed lunar craters remains open.

NO WATER ICE DETECTED FROM LUNAR PROSPECTOR IMPACT

The controlled crash of NASA's Lunar Prospector
spacecraft into a crater near the south pole of the Moon
on July 31 produced no observable signature of water,
according to scientists digging through data from Earth-
based observatories and spacecraft such as the Hubble
Space Telescope.

This lack of physical evidence leaves open the
question of whether ancient cometary impacts delivered
ice that remains buried in permanently shadowed regions
of the Moon, as suggested by the large amounts of
hydrogen measured indirectly from lunar orbit by Lunar
Prospector during its main mapping mission.

Research group leaders from the University of Texas
at Austin announced their results today at the annual
meeting of the American Astronomical Society's Division
for Planetary Sciences meeting in Padua, Italy.

In a low-budget attempt to wring one last bit of
scientific productivity from the low-cost Lunar
Prospector mission, NASA worked with engineers and
astronomers at the University of Texas to precisely crash
the barrel-shaped spacecraft into a specific shadowed
crater. NASA accepted the team's proposal based on
successful scientific peer review of the idea and the
pending end of the spacecraft's useful life, although the
chances of positive detection of water were judged to be
less than 10 percent.

Worldwide observations of the crash were focused
primarily on using sensitive spectrometers tuned to look
for the ultraviolet emission lines expected from the
hydroxyl (OH) molecules that should be a by-product of
any icy rock and dust kicked up by the impact of the 354-
pound spacecraft.

"There are several possible explanations why we did
not detect any water signature, and none of them can
really be discounted at this time," said Dr. Ed Barker,
assistant director of the university's McDonald
Observatory at UT Austin, who coordinated the observing
campaign. These explanations include:

the spacecraft might have missed the target area;

the spacecraft might have hit a rock or dry soil at
the target site;

water molecules may have been firmly bound in rocks as
hydrated mineral as opposed to existing as free ice
crystals, and the crash lacked enough energy to separate
water from hydrated minerals;

no water exists in the crater and the hydrogen
detected by the Lunar Prospector spacecraft earlier is
simply pure hydrogen;

studies of the impact's physical outcome were
inadequate;

the parameters used to model the plume that resulted
from the impact were inappropriate;

the telescopes used to observe the crash, which have a
very small field of view, may not have been pointed
correctly;

water and other materials may not have risen above the
crater wall or otherwise were directed away from the
telescopes' view.

Although the crash did not confirm the existence of
water ice on the Moon, "this high-risk, potentially high-
payoff experiment did produce several benefits," said Dr.
David Goldstein, the aerospace engineer who led the UT
Austin team. "We now have experience building a
remarkably complex, coordinated observing program with
astronomers across the world, we established useful upper
limits on the properties of the Moon's natural
atmosphere, and we tested a possible means of true 'lunar
prospecting' using direct impacts."

Lunar Prospector was launched on Jan. 6, 1998, from
Cape Canaveral Air Station, FL, aboard an Athena 2
rocket. In March 1998, mission scientists announced
their first tentative findings of the presence of water
ice in shadowed craters near the Moon's south and north
poles. They estimated later that up to six billion
metric tons of water ice may be buried in these craters
under about 18 inches of soil, in more concentrated
deposits than originally thought. However, the evidence
was indirect, they cautioned, based on reasonable
scientific assumptions given the levels of hydrogen
detected, from which water ice is inferred.

Since then, Prospector data have also been used to
develop the first precise gravity map of the entire lunar
surface. While the Moon's magnetic field is relatively
weak, Prospector has confirmed the presence of local
magnetic fields that create the two smallest
magnetospheres in the Solar System. Another scientific
landmark is the assembly of the first global maps of the
Moon's elemental composition.

The $63 million Lunar Prospector mission was led by
Dr. Alan Binder of the Lunar Research Institute, Tucson,
AZ, and managed by NASA's Ames Research Center in Moffett
Field, CA. It was built by Lockheed Martin Missiles &
Space, Sunnyvale, CA. Other participating organizations
included the Department of Energy's Los Alamos National
Laboratory, NM, and NASA's Goddard Space Flight Center,
Greenbelt, MD, and Jet Propulsion Laboratory, Pasadena,
CA.

University of Texas-Austin
Austin, Texas 78713-7509

October 12, 1999

New efforts to find evidence of water on the moon came up dry, researchers
at The University of Texas at Austin announced Wednesday (Oct. 13)

AUSTIN, Texas -- New efforts to find evidence of water on the moon came up
dry, researchers at The University of Texas at Austin announced Wednesday
(Oct. 13). But their research efforts have laid the groundwork for further
investigations, as well as demonstrating a potentially useful new method
for lunar prospecting.

The UT Austin group announced its findings at the annual meeting of the
American Astronomical Society's Division for Planetary Sciences in Padua,
Italy. In what was virtually a no-budget attempt to vaporize ice suspected
to exist at the South Pole of the moon, NASA worked with engineers and
astronomers at UT Austin to crash the space agency's successful Lunar
Prospector spacecraft in a specific polar crater in a precise manner.

The July 31 crash took only seconds. But the painstaking analysis of
information recorded by more than a dozen professional Earth- and
space-based telescopes required several months. Hundreds of amateur
telescope owners also observed as the spacecraft plunged into a
permanently shadowed crater near the pole.

"As expected, we didn't make a big splash, or we all would have seen a
water signal quickly," said Dr. David Goldstein, leader of the UT Austin
team that proposed the crash. Goldstein, an aerospace engineer, is an
associate professor in the UT Austin Department of Aerospace Engineering
and Engineering Mechanics.

Prior to the crash, Goldstein worked to model and calculate the final
orbit and crash of the Lunar Prospector with Dr. R. Steven Nerem, also
an aerospace engineer and an associate professor in the department;
aerospace engineering students J. Victor Austin and Jeong Yon Shim; and
NASA engineers. Dr. Edwin S. Barker, research scientist with the UT
Austin Department of Astronomy, coordinated worldwide observations of
the crash.

Last year, the Lunar Prospector team reported the spacecraft's instruments
had revealed possible signs of frozen water at the moon's north and south
poles. At that point, the UT Austin team came up with the idea of a
controlled crash.

"The way we aimed to detect water -- or its signature -- was through
sensitive spectrometers tuned to look for the ultraviolet spectral
emission lines expected from the hydroxyl (OH) molecules," said Barker.
Barker and Shim analyzed the spectra from NASA's Hubble Space Telescope,
McDonald telescope and the Keck I in Hawaii.

Scientists and engineers working on the project knew from the beginning
that there was a low probability of proving existence of water on the moon
and the research discussed in Padua did not confirm water's existence.
But the researchers said several benefits resulted from this potentially
high-payoff experiment, including:

Development of a coordinated observation program among many observers
working together throughout the world, including more than a dozen
professional teams of astronomers;

Establishment of useful upper limits on estimates of the density of
the Moon's thin natural atmosphere; and

Establishment of a possible means of lunar prospecting using direct
impacts.

"If we can identify any other spacecraft whose useful life is over, but may
have sufficient fuel and controllability to repeat the impact experiment,
we'd like to do it again," said Goldstein.

The team offered several possible reasons why the telescopic information
has yielded no evidence of water, however, there is no way of knowing
which of them might apply:

The spacecraft might have missed the target;

The spacecraft might have hit a rock or dry soil at the target site;

Water molecules may be firmly bound in rocks as hydrated minerals,
rather than existing as free ice crystals, and the crash lacked enough
energy to separate water from hydrated minerals;

No water exists in the crater and the hydrogen detected earlier by the
Lunar Prospector spacecraft was simply pure hydrogen;

Pre-impact studies were inadequate;

Parameters used in modeling the vapor gas dynamics were inadequate;

The telescopes, which have a very small field of view, may not have been
pointed correctly;

Water and other materials may not have risen above the crater wall or
otherwise may have jetted away from the telescopes' view.

For a more detailed discussion and history of the project, plus
illustrations (including target site, expected evolution of vapor cloud
and animations) see:

Prospector Crash Created No Dust Cloud

The crash of the Lunar Prospector spacecraft more than a month
ago failed to create an observable cloud of dust, but the search for
water thrown up by the impact continues, sciences say.

David Goldstein, the University of Texas at Austin professor
who first proposed the deliberate crash of the spacecraft into a
permanently-shaded area near the lunar south pole, said that no
professional nor amateur observers saw a cloud of dust that could have
been created by the impact.

On the other hand, Goldstein noted, a lack of a dust plume
created by the July 31 crash might improve chances of detecting water
that was lifted into space by the force of the impact.

"The only way we could have seen dust would be if it had risen
above the bright lunar surface and we might have seen it against the
black of the sky," he said in a NASA Science News report September 3.
"If we had seen a dust plume it might have meant that the spacecraft
hit the near rim or the far rim of the crater."

Scientists had targeted a deep, permanently-shadowed region of
a 50-km (30-mi.) crater near the south pole, where water ice is
believed to exist, based on data from Prospector's neutron
spectrometer. A crash in that area would have been unlikely to create
a visible dust plume.

Data collected by groundbased and orbiting telescopes is being
examined by astronomers to look for spectroscopic evidence of water.
"Right now we don't know that water ice was not observed -- it might
be in the data somewhere," he said. "We're still looking closely at
spectra from the Hubble Space telescope, the McDonald Observatory, and
Keck I."

If water is detected, it would eliminate nearly all doubts
that water ice exists in shadowed regions of the lunar poles. The ice
is thought likely to exist based on the Prospector data as well as
earlier radar observations by the Clementine spacecraft, but the
existence of water could only be strongly inferred from those data,
and other scientists had proposed alternatives, from solar wind
hydrogen to hydrated cement-like minerals, to explain the data.

However, a failure to detect water from the Prosector crash
does not mean water does not exist on the Moon. Prior to the crash
Goldstein estimated that the experiment had only a ten percent chance
of detecting water ice, because of the uncertainties in the
distribution of ice in the craters.

Goldstein said a University of texas team that observed the
crash should report on its efforts to detect water and hydroxyl (OH),
an ion formed by the disassociation of water, within the next several
weeks.

NASA Space Science News for September 3, 1999

The Case of the Missing Moon Water: Lunar Prospector failed to kick up
a visible dust cloud when it crashed into the Moon, but that doesn't
mean it failed to strike water. Astronomers are still sifting through
their data for elusive signatures of a tenuous water vapor cloud that
may have resulted from the crash.

NASA Ames Research Center
Moffett Field, CA 94035

Lunar Prospector Mission Update

July 31, 5:45 A.M. PDT

Lunar Prospector, "the little spacecraft that could," can't anymore. As a
room full of viewers and observatories from around the world looked on, the
LP Mission Control team successfully ended the Lunar Prospector mission at
2:52:00.8 a.m. PDT on July 31 when the spacecraft slammed into a deep
crater near the south pole of the moon.

No visible debris plume was reported and it may be several days before data
from ground- and space-based observatories and telescopes can be analyzed
to determine if any water vapor was liberated by the impact.

Mission Control at NASA's Ames Research Center indicated that they are
confident the small, spin-stabilized spacecraft hit its intended target
precisely. The failure to reacquire a signal from the vehicle at the time
it would have emerged from the dark side of the moon is proof that impact
occurred. The absence of a visible debris plume is not a negative result.
In fact, it increases the likelihood that the spacecraft impacted deep into
the intended target crater.

The final sequence of events for Prospector began at 1:17 a.m. PDT when the
Mission Control team successfully loaded a 60-minute pre-programmed
countdown into Prospector's internal clock to initiate the final burn
sequence. At 2:00 a.m. PDT, final loss of signal from Prospector occurred,
as planned, when the spacecraft passed behind the moon for the last time.
Alan Binder, Lunar Prospector Principal Investigator observed, "we don't
want to hear from Prospector again - if we do, we've missed our mark." He
was not to be disappointed.

The scheduled 4 minute 36.5 second burn was executed behind the moon at
2:17 a.m. "Prospector's engines should be burning full -- preparing to
de-orbit," said Binder. "It is now hurtling towards its destiny at
approximately 1.7 kilometers per second on a ballistic trajectory that will
take it to its target crater."

The spacecraft's key scientific instruments continued to send data until
the very end when signal was lost. "Once again, Prospector has done
everything we have asked of it," said Binder. "This mission provided ten
times better data than we expected. The spacecraft performed flawlessly to
its very end. Scientists will be analyzing the tremendous volume of
valuable data obtained for years to come," he concluded.

Analysis of data obtained during the mission-end experiment will be ongoing
for days, and possibly weeks, to come. At the completion of that analysis,
scientists will have a much better idea if Prospector has, in fact,
provided the definitive evidence of water ice on the moon that they were
seeking. A positive result may have the potential to open up expanded
possibilities for solar system exploration. Failure to prove conclusively
that water ice exists in the lunar polar regions by no means suggests that
it is absent, according to mission scientists. It simply means that this
particular bold experiment, acknowledged as high payoff but also with low
probability of success, has not provided the conclusive evidence that was
being sought.

Amateur astronomers target Lunar Prospector: While professional
astronomers watch for a nearly transparent cloud of water vapor,
amateurs will monitor the Moon's south pole for visible signs of
Lunar Prospector's crash.

A Stay of Execution for Lunar Prospector: The Lunar Prospector
spacecraft survived the partial lunar eclipse of July 28 and is on track
for a planned collision with the Moon on July 31. This story
includes a video clip of this morning's eclipse as seen from Australia
and new impact simulations from the University of Texas at Austin
which suggest that the debris plume on July 31 may rise as high
as 30 km above the target crater's rim.

7/28/99

The Lunar Prospector spacecraft continues to collect good science data in
the extended mission orbit. Two of five science instruments are on: the
Magnetometer (MAG) and the Electron Reflectometer (ER). The spectrometers
were powered off today as part of the eclipse power sharing activities as
described below.

The Lunar Prospector orbit was trimmed successfully Monday. This maneuver
raised the altitude of periapsis by about 5 km to allow the spacecraft to
safely orbit through the rest of the week. A brief timeline is below.
Times are GMT, on DOY 207 [7/26/99]:

After the maneuver, the MAG/ER was configured to collect high resolution
data during the full moon passage. A total of 27 commands were transmitted
with no anomalies.

The LP spacecraft successfully survived today's lunar eclipse. Because the
moon passed through the earth's shadow, the time of no sunlight was
increased from the once per orbit lunar shadow duration of 36 minutes, to
67 minutes. For another 2:31, the sun was partially eclipsed by the earth,
preventing the normal recharge of batteries. The spacecraft was not
designed to survive this eclipse.

To increase the chance of survival, the spectrometer instruments were
turned off, reducing the load. Because they would get very cold during the
eclipse while they were turned off, they will not be turned on again during
the last 3 days of the mission. The impact to their science analysis will
be negligible. The MAG/ER was left on so that it could continue to get the
high resolution full moon data through the end of the mission.

Other non-essential loads were powered off: the pressure transducer which
measures the propellant tank pressure, and the earth-moon limb sensor.
These were turned back on at the end of the event. Also turned off was the
primary heater relay. This prevented the highest load of the spacecraft,
the propellant tank heaters, from coming on at a time when the battery was
unable to support the load. This relay was turned back on at the end of
the event as well.

The spacecraft transmitter is the second highest load on the spacecraft,
and it was turned off for every occultation (when the s/c is behind the
moon as seen from the tracking station), plus extra time as needed to allow
battery recharge. It was turned on as much as power allowed to prevent it
from getting too cold as well as to allow collection of data to monitor the
spacecraft status.

Activities are listed below, times are GMT, DOY 209 (7/28/99). Umbra is
when the entire sun is blocked by the earth as seen from the spacecraft.
Penumbra is when only part of the sun is blocked. Occultation times are
not listed, but they overlap closely with the lunar shadow events.

The next activity is the spin-up, scheduled for tomorrow, 7/29 at 15:32
GMT. This will be the first step in setting the spacecraft up for the
targetted impact. Impact is now scheduled for 09:51 GMT on 7/31 (one
minute earlier than reported last week). It was moved up to optimize
timing with Hubble Space Telescope observations.

NASA GODDARD SHOOTS FOR "HOLE IN ONE" ON THE MOON, HOPES TO FIND WATER TRAP

Numerous ground and space-based observatories will assist NASA in a search for
water in material hurled upward from the planned impact of the Lunar Prospector
(LP) spacecraft in the early morning hours of July 31. Flight dynamics
controllers at NASA's Goddard Space Flight Center, Greenbelt, Md., are guiding
the spacecraft to the designed crash inside a crater near the south pole of the
Moon. Scientists believe there may be water ice near the surface in the crater
bottom, which is in permanent shadow.

Energy from the impact, equivalent to crashing a two-ton car at more than 1,100
miles per hour, may liberate up to 40 pounds of water in vapor form, experts
predict.

"While the probability of success for such a bold undertaking is low, the
potential science payoff is tremendous," said Dr. Guenter Riegler, Director of
the Research Program Management Division in the Office of Space Science at NASA
Headquarters, Washington, D.C.

"This impact is unlike the other Moon missions of the 1960's and 70s' where the
incoming trajectory was almost perpendicular to the lunar surface," said David
Folta, the Goddard Lunar Prospector Team Lead in the Guidance, Navigation, and
Control center (GN&C). "The difficulty of this maneuver is that Lunar Prospector
is already in orbit about the Moon and the angle of impact is only 6.5 degrees.
Achieving this grazing impact is similar to hitting the middle of a pie pan laid
on home plate with a baseball thrown from second base at over 100 miles per
hour. In this case, LP is the baseball and the rim of the pie pan represents the
rim of the crater, almost four kilometers above the floor of the crater. The
tolerance for error in the final trajectory is plus or minus three percent. Any
greater error in the negative direction will result with an impact with the
crater rim before reaching its destination. A larger error in the positive
direction will result in a complete miss of the targeted crater."

"The Hubble Space Telescope's STIS (Space Telescope Imaging Spectrograph)
instrument will monitor the impact site, searching for a glow of ultraviolet
light emitted by the OH molecule (which consists of one atom each of oxygen and
hydrogen)," said Dr. David Leckrone, senior scientist for Hubble at Goddard.
"The OH would be produced by the breakup of water molecules (H2O) by ultraviolet
sunlight, which is intense in the vacuum of space. This is the same technique
astronomers use to look for the signature of water in comets. The OH emission
tends to be bright and easily detected, compared to other indicators of water
that would be available to HST. "From its vantage point above the Earth's
atmosphere, and with its unsurpassed image clarity and sensitivity, HST is well
suited for this job. It will be a difficult observation, but we've taken extra
care to assure that it is executed correctly. It's hard to predict what to
expect. But the idea of performing a "controlled" experiment on the surface of
the Moon, monitored by an array of earth and space-based telescopes, is exciting
in its own right. Certainly, the direct verification of the existence of water
on the Moon would be an important milestone in the exploration of the solar
system," said Leckrone.

NASA's Submillimeter Wave Astronomy Satellite (SWAS) will join the hunt for
water. "SWAS is the only observatory that can directly confirm the presence of
complete water molecules by detecting characteristic microwave radiation from
water vapor," said Dr. Gordon Chin, SWAS Project Scientist at Goddard. "The
observations will be challenging. We can't follow our normal procedure of
pointing the spacecraft at its target using guide stars because the Moon is
too bright -- it would blind the star sensor. Instead, we must rely on the
spacecraft's gyroscopes and a detailed knowledge of the Moon's position
relative to SWAS. However, SWAS is extraordinarily sensitive to water. If
water is present, and there are no unusual complications, we should detect
it even in the small amounts predicted."

To reach the crater target, two maneuvers are used, one to raise the highest
part of the orbit to increase the incoming angle into the crater and to adjust
the time of impact, and another that targets the exact latitude, longitude, and
angle of impact. As with the primary and extended mission, the Goddard GN&C is
providing the trajectory design, maneuver generation, and navigation for this
event. Folta has only several hours to re-target the final inbound flight
before final impact July 31 at 5:51 a.m. EDT using the navigation data
provided by Mark Beckman, also of the GN&C.

This effort to gain additional science data about the Moon's composition was
proposed to NASA by an external team of engineers and astronomers led by Dr.
David Goldstein of the University of Texas at Austin.

"We have had an interest in thin planetary atmospheres for a while and how
comet impacts might have led to the accumulation of water ice at the lunar
poles," said Goldstein. "We were thinking about how the Leonid meteorite
impacts on the Moon might be seen when we realized that since the Lunar
Prospector mission was scheduled to end anyway, Lunar Prospector could
become an artificial meteorite in which the time, position and energy of
impact would be precisely known. Our team at the U. of Texas suggested the
idea to the Lunar Prospector team, and they were enthusiastic about the
opportunity to produce significant scientific results right up until the
very end of the mission."

Spacecraft crash to end productive mission

LOS ALAMOS, N.M., July 27, 1999 -- Scientists at the Department of Energy's
Los Alamos National Laboratory hope the controlled crash of NASA's Lunar
Prospector spacecraft into the moon Saturday will provide final proof for
what they believe they have already measured: the presence of frozen water
on the moon.

Mission scientists acknowledge a small chance of success, but they hope the
crash will kick up a cloud of debris that includes a small quantity of water
buried at the lunar poles. Earth-based telescopes and the Hubble Space
Telescope will scan the debris cloud for signs of the water.

Los Alamos scientists built three of the instruments aboard Prospector,
including the one whose measurements quantified the amount of water-ice
that could reside in numbingly cold lunar craters. The two other instruments
measure geologic composition and outgassing from seismic events.

Lunar Prospector, part of NASA's Discovery Program of low-cost, fast-track
space missions, was envisioned and is led by Alan Binder of the Lunar
Research Institute.

The technology and skills behind Los Alamos' three on-board spectrometers --
one for measuring neutrons, one for gamma rays, and one for alpha particles
-- were born in Los Alamos' nuclear weapons mission and honed on various
satellites for monitoring compliance with weapons nonproliferation treaties.
Astrophysical and solar system studies have been a natural follow-on for
these capabilities.

"Lunar Prospector represents the first time neutron spectroscopy has been
applied to planetary exploration," said Bill Feldman, leader of the Los
Alamos team. Feldman has been ecstatic since the first data came rolling
in.

"The data returned have been absolutely beautiful," Feldman said. "This is
everything one could have dreamed of."

The neutron measurements rely on high-energy cosmic rays slamming into
the lunar soil. The cosmic rays generate a microscopic spray of nuclear
particles, including neutrons. The neutrons bounce around in the soil,
losing a little energy in each collision, before emerging from the soil
and heading upward to where an orbiting spacecraft can detect them.

The Los Alamos spectrometer measures neutrons in three energy ranges:
fast, medium and slow. The relative proportion of the three neutron
energies is a key indicator of the material in the lunar soil.

In particular, hydrogen is very efficient at moderating the energy of the
neutrons; over regions with enhanced hydrogen the detector receives a
deficit of medium-energy neutrons. Scientists believe water molecules
are the most likely form for any hydrogen resident in the lunar soil.

The Lunar Prospector team has now combined data from the craft's
high-altitude and low-altitude orbits. The lower-altitude observations
provide higher-resolution maps.

"Both results argue for small, unresolved deposits of hydrogen around
the northern pole," Feldman said. "The concentrations extend over a
larger area around the southern pole, and these data are consistent
with islands of enhanced hydrogen deposits -- which we interpret as
water ice -- immersed within regolith evenly spread with enhanced
hydrogen."

The scientists estimate a hydrogen abundance equivalent to about
two billion tons of water in total near the moon's poles. Soil bearing
enhanced hydrogen and perhaps frozen water would allow engineers to
contemplate ways to mine this precious resource to support colonization.

In research led by Los Alamos' David Lawrence, scientists have used the
gamma-ray data to trace out key elements in the lunar soil that bear on
the moon's formation and evolution. Cosmic ray-sparked collisions create
many of the gamma rays that emerge from the lunar soil, but one key
element, thorium, generates its own distinct gamma ray as a result of
radioactive decay.

Thorium is part of a chemical amalgam dubbed "KREEP." KREEP represents
the last part of a planet's or moon's molten mix to solidify. When it freezes,
the KREEP is sandwiched between the relatively lightweight material that
floated to the top of the melt to form the crust and the heavier material
that sank to form the mantle.

Thorium or other KREEP constituents seen on the surface are evidence of
volcanic processes or large meteor impacts that can punch through the
crust and dredge up material from the interior.

"We've conclusively demonstrated that the surface occurrence of KREEP
is mainly confined to the nearside region in and around the Imbrium
basin," Lawrence said. Imbrium basin, one of the distinctive dark areas
that make up the "man in the moon," was created by an ancient meteor
impact nearly four billion years ago.

"One possible implication of this result is that KREEP was not uniformly
distributed over the entire moon, but mostly confined to the nearside
region," Lawrence said.

On the moon's far side, the highest thorium abundance occurs near
Imbrium's antipode, the surface point defined by a line drawn from
Imbrium, through the moon's center and out the other side. This suggests
material ejected by the Imbrium impact traveled around the moon and
settled out at the antipode.

"These data will play an important part in refining theories for how the
moon formed and evolved," Lawrence said.

Los Alamos' third instrument aboard Lunar Prospector is an alpha particle
spectrometer. Alpha particles are emitted in various radioactive decay
processes, including that of radon, a gas that accumulates underground
and can be released in seismic events. Scientists intend to analyze the
data for signs of such seismic activity, but have not yet had time to do
so.

The most recent scientific results from the Los Alamos team will appear
in the Journal for Geophysical Research and Geophysical Research Letters.
Team members include Feldman, Lawrence, Rick Elphic, Bruce Barraclough
and Tom Prettyman. Sylvestre Maurice and Isabel Genetay of the Midi-
Pyrenees Observatory in France are co-authors.

This work has been supported by the Department of Energy, NASA,
Lockheed-Martin and the Observatoire Pic Midi.

Los Alamos National Laboratory is operated by the University of California
for the U.S. Department of Energy.

CREATIVE IMPACT EXPERIMENT TO MARK END OF LUNAR PROSPECTOR

In one final blast of scientific productivity, NASA's Lunar
Prospector mission will end abruptly in the early morning hours of
July 31 with a controlled crash into a crater near the south pole
of the moon.

The scripted, violent end of Lunar Prospector at 5:51 a.m.
EDT is designed to provide direct evidence of the existence of
water ice in permanently shadowed craters near the moon's poles.

Scientists hope that the estimated 3,800-mph impact will
exhume water vapor and rocky debris that may be detectable for
several hours, although data analysis could take days or even
weeks if the signal is faint. Coordinated observing teams will
use NASA's Hubble Space Telescope and Submillimeter Wave Astronomy
Satellite, and ground-based instruments including the McDonald
Observatory in Texas and the Keck telescope in Hawaii, to seek
signs of the water vapor or its byproducts.

While the probability of successful detection is estimated to
be less than 10 percent, it will be a fittingly creative finish to
a low-cost Discovery Program mission that has exceeded all
expectations after more than 6,800 lunar orbits in 18 months.

"Regardless of the outcome of this final bold experiment,
Lunar Prospector has yielded a gold mine of science data," said
Dr. Henry McDonald, director of NASA's Ames Research Center,
Moffett Field, CA, which has managed the mission. "We now have
invaluable global maps of the moon's gravitational and magnetic
fields, and the distribution of its key elements, giving us a much
better understanding of the origin, evolution and composition of
our rocky neighbor."

Launched on Jan. 6, 1998, from Cape Canaveral Air Station,
FL, aboard an Athena 2 rocket, Lunar Prospector reached the moon
in four days. Shortly after entering orbit over the lunar poles,
its five science instruments began expanding the limited
equatorial measurements made by the Apollo command modules into
global, high-resolution data sets.

Lunar Prospector's data gathering has resulted in a series of
discoveries and new scientific tools, including:

tentative evidence that water ice exists in shadowed craters near the moon's south and north poles.

the first precise gravity map of the entire lunar surface.

confirmed the presence of local magnetic fields that create the two smallest magnetospheres in the Solar System.

the first global maps of the moon's elemental composition.

In exceeding its design life, the $63 million Prospector
mission has exhausted the bulk of its fuel and battery power.
Although the drum-shaped probe will have a mass of only 354 pounds
(161 kilograms) at the end, its impact energy will be equivalent
to crashing a two-ton car at more than 1,100 miles per hour.

Further information about Prospector and its science data return
can be obtained at the project Web site.

Additional information about the end-of-mission sequence is
available at:

Dr. Alan Binder of the Lunar Research Institute, Tucson, AZ,
led the Lunar Prospector team. The spacecraft was built by
Lockheed Martin, Sunnyvale, CA. Other participating organizations
include the Department of Energy's Los Alamos National Laboratory,
NM; NASA's Goddard Space Flight Center, Greenbelt, MD; and NASA's
Jet Propulsion Laboratory, Pasadena, CA. An external team of
engineers and astronomers led by Dr. David Goldstein of the
University of Texas at Austin will conduct the end-of-mission
telescopic observations and data analysis.

TUCSON, ARIZ. -- When Lunar Prospector crash dives into the moon's south
pole early Saturday morning, Tucson-based observers hope for clear skies and
a good view.

Also watching intently will be a University of Arizona planetary scientist
who is sending a memorial tribute aboard the satellite.

UA astronomers and others observing near Tucson are part of an extensive
network that will be searching for water vapor in Lunar Prospector's impact
plume.

Since its launch in January 1998, Lunar Prospector has scored a number of
scientific coups, as well as a followup confirmation of possible water-ice
deposits at the north and south lunar poles. The question is whether the
hydrogen it detected exists in water ice or in hydrogen-containing compounds
called hydrates. Not all scientists agree this experiment will definitively
answer the question. (For more on that, see news online at
http://www.space.com/news/planetarymissions/moon_doubt.html) However, the
answer is of scientific and practical interest for future space explorers.
Sending a pint of water to the moon costs $10,000. So picking it up at the
south lunar pole could turn out to be one of the biggest bargains in this
part of the solar system.

Aerospace engineers at the University of Texas in Austin were the first to
conceive of crashing Lunar Prospector into a frigid, shadowed crater at the
lunar south pole just before the satellite runs out of fuel. The 354-pound
(161 kg) Lunar Prospector will be traveling at 3,600 mph (5,793 kph) or
faster. If the impact plume it generates is large enough - and that's a big
"if," scientists emphasize - observers might discover the first irrefutable
proof of water on the moon. But scientists caution that it may take weeks or
months of data crunching before this is confirmed.

The project was approved by officials at the NASA Ames Research Center in
Moffett Field, Calif., which manages the mission, and at NASA Headquarters
in Washington, D.C. Observers will watch for the impact plume with
telescopes at several locations including Texas, California, and Hawaii.
Those involved will include the Hubble Space Telescope, the Keck 1
telescope, and the MacDonald Observatory telescopes.

If monsoon clouds don't obscure their views. Ann L. Sprague and Stephen M.
Larson, both of the UA Lunar and Planetary Laboratory (LPL), will observe
with telescopes in the Santa Catalina Mountains north of Tucson. Other
astronomers will use the McMath-Pierce and WIYN telescopes on Kitt Peak,
southwest of Tucson.

Sprague and her colleagues will use the UA's 1.54 meter (61-inch) telescope
on Mount Bigelow to monitor sodium in the moon's diaphanous atmosphere
before, during and after impact. They are trying to learn more about the
structures of the thin atmospheres on the moon and planet Mercury by using
spectroscopy to look for sodium and other elements..

Larson will install special filters on the 1.52 -meter (60-inch) NASA
reflector telescope on Mount Lemmon to look for OH, a byproduct of water.
"Given the moon's low declination and the monsoon weather, I don't expect
anything close to Keck or HST results, but I'll be looking anyway," he said.

The 61-inch telescope was built by the late Gerard Kuiper, who founded LPL,
in the early 1960s to survey the moon in preparation for the lunar
spacecraft missions being proposed at that time. Kuiper died in 1973. His
ashes were placed at the 61-inch telescope during a small LPL celebration
last month. The Mount Lemmon 60-inch telescope, also built by Kuiper, was
used for lunar laser ranging observations after Apollo 11.

SHOEMAKER TRIBUTE ABOARD LUNAR PROSPECTOR

The filters Larson will use are the same ones he used in photographing Comet
Hale-Bopp from Tucson in April 1997. One of those images rides on a small,
polycarbonate capsule that is hitching a ride to the moon aboard Lunar
Prospector. The capsule is wrapped in a piece of brass foil inscribed with
Larson's image of Comet Hale-Bopp, an image of Meteor Crater in northern
Arizona and a passage from Shakespeare's "Romeo and Juliet."

Inside the capsule are the ashes of the late Eugene M. Shoemaker. Shoemaker
was a pioneering planetary geologist famous for his work on extraterrestrial
impacts and for his later collaboration with his wife, Carolyn, in the study
and discovery of comets. He was killed in a July 1997 auto accident in
Australia. LPL Associate Professor Carolyn C. Porco conceived, designed and
produced this tribute honoring Shoemaker in time for the Lunar Prospector
launch only months after Shoemaker's death.

"It was legend among planetary scientists that Gene's life-long dream was to
go to the moon and study its geology firsthand," Porco said. "At his
journey's end - thirty years to the month after humans first set foot on the
moon - Eugene M. Shoemaker will become the first inhabitant of Earth to be
sent to rest on another celestial body," Porco said.

Porco has produced replicas of the Shoemaker tribute foil for museum
display. They have been sent to the Smithsonian Air and Space Museum in
Washington, D.C.; the Adler Planetarium in Chicago, the Hayden Planetarium
in New York and the U.S. Geological Survey headquarters in Reston, Va.,

Copies also have been given to the U.S. Geological Survey Gene Shoemaker
Building, which is under construction in Flagstaff, Ariz.; the Meteor Crater
Visitor Center; NASA Ames Research Center; NASA Headquarters; and the UA
Lunar and Planetary Laboratory.

Additional copies have gone to Carolyn Shoemaker: NASA Chief Administrator
Dan Goldin; Wesley Huntress, formerly head of the NASA Space Sciences
Division; and Bruce Babbitt, U.S. Secretary of the Interior.

For more information on the Shoemaker tribute, see the UA News Services
release of Jan. 6, 1998, "Lunar spacecraft carries ashes, special tribute to
Shoemaker," at:

Moon burial for geologist

US geologist Gene Shoemaker, killed in a 1997 car crash in Australia, is
soon to become the first person to be buried on another planet.

When the tiny Lunar Prospector spacecraft crashes into a dark crater near
the Moon's south pole on Saturday, it will deposit onto the lunar surface
the ashes of the pioneering astro-geologist.

Major impact

He was a legend among geologists. Almost on his own he invented the science
of the study of cosmic impacts and he played a key role in training the
Apollo moonwalkers to explore the Moon in a scientific manner.

The case against water ice on the moon

By David F. Salisbury

On July 31, NASA intends to crash the Lunar Prospector spacecraft into a small
crater near the moon's south pole. The 354-pound spacecraft will be traveling
at about 3,800 miles per hour when it plows into the lunar surface. The
purpose for such a violent end to the $63-million mission is to find out
whether there is any water ice hidden in the bottom of the crater, which is
shrouded in perpetual shadow.

But two Stanford researchers predict that, rather than ice, the spacecraft
is more likely to hit deposits of "hydrous" lunar minerals that contain the
constituents of water chemically bound into their crystal structure. Von
R. Eshleman, professor emeritus of electrical engineering, and George A.
Parks, professor emeritus of geological and environmental sciences, argue
that water ice left on the moon from past cometary impacts has most likely
combined chemically with the water-free powdered rock that covers most of
the lunar surface. They outlined their reasoning in a letter that was
published in the July 23 issue of the journal Science.

NASA scientists and other advocates for establishing a permanent base on the
moon are eager to find a source of accessible water because it could provide
water, oxygen and rocket fuel for human colonists. Water ice would be ideal
for this purpose. But, if Eshleman and Parks are right, "the constituents of
water are there, but obtaining water would require large amounts of energy
and so would be much harder and more expensive," says Eshleman, who has been
involved with radioscience investigations of the moon and planets since the
1950s.

When Prospector crashes on the moon, the Hubble space telescope, along with a
number of its space and Earth-based cousins, will be focused on the site. They
will be equipped with sensitive instruments that can determine the composition
of the plume of lunar material that the Prospector kicks up. Mission scientists
predict that this plume could contain as much as 40 pounds of water, which
sunlight should break down into hydrogen and hydroxyl ions. If the cloud
contains significant amounts of hydroxyl ions, mission scientists argue that
it will verify their assertion that large amounts of water ice exist in the
region, something that they have predicted based on indirect evidence
collected by the spacecraft's instruments.

The two Stanford scientists argue that this test, however dramatic, will not
be definitive. If their theory is correct, they consider it unlikely that the
spacecraft will kick up significant signs of water. But it is not impossible
that the energy from the impact might cause some of the particles of hydrous
rock to chemically dissociate, producing hydrogen and hydroxyl ions and
reconstituting some of the water that it has held in chemical bondage, perhaps
for billions of years.

The idea that the polar craters on the moon and the planet Mercury may
contain water ice dates back to the early 1960s. Scientists recognized that
the bottoms of some of these craters must be shrouded in perpetual shadow,
shielded from sunlight by their uplifted rims. These shaded areas should have
a constant temperature of around 170 degrees Celsius below zero, making them
the coldest places on their respective worlds. As a result, each time Mercury
or the moon was hit by a water-bearing comet, the water molecules it
deposited would either end up in one of these "cold sinks" or escape into
space.

In fact, radar observations of Mercury appear to have found water ice in
some of its polar craters. At least, the radar reflections closely resemble
those produced by ice-covered objects, like several outer planet satellites.
On the moon itself, however, the evidence has been more ambiguous.

The strongest evidence in favor of the existence of ice on the moon is
measurements taken with an instrument called a neutron spectrometer flown
aboard the Prospector. This instrument cannot detect water ice directly, but
has measured excess levels of hydrogen in the lunar polar regions.

Radar images taken of the lunar poles, however, have not found the
characteristic signature of ice found on Mercury or other ice-covered
objects in the solar system. So proponents have explained the radar returns
as coming from "stealthy ice," ice that is either buried below a layer of
lunar dust or mixed with lunar material to some depth.

Eshleman and Parks consider this highly unlikely, pointing out that the
hydrogen detected by Prospector is to be expected if all the ice has
combined with surface minerals. In the past, scientists thinking about
this situation have simply assumed that water molecules freezing out
would clump together to form ice. They haven't given any thought to the
chemical nature of the material the ice would be forming on or the nature
of the chemical interactions that might occur.

The Stanford researchers point out that the moon rocks brought back to
Earth during the Apollo program indicate that the material covering the
lunar surface is anhydrous, that is, it doesn't contain any water at all.
Due to continual micrometeorite bombardment, this material has been ground
up into a fine powder. "The surface of these particles is covered with
broken bonds that will grab hold of any water molecules that come along,"
says Eshleman. Although no samples were returned from the lunar poles,
there is no reason for the material there to be basically different from
that which covers the rest of the moon, he argues.

According to Eshleman, this anhydrous lunar material contains two of the same
ingredients as Portland cement and should have similar properties. While the
lunar material is naturally anhydrous, Portland cement is made from common
earth materials that are heated to drive out all the water.

"What happens when you put an ice cube on a layer of Portland cement in a
vacuum and at a very low temperature?" Eshleman asks. "We predict that the
ice will eventually disappear as it is absorbed by the cement."

Eshleman and Parks predict that the lunar material should react in a similar
fashion. What is more, they calculate that this is a one-way process:
Once water is incorporated into the lunar minerals, the resulting material
would be extremely stable.

Furthermore, the radar reflection of the resulting hydrous material should be
nearly identical to that of the anhydrous material, and so can explain the
radar data from the poles without having to bury or mix the ice as proposed
by the Prospector team, the Stanford scientists say.

The response of the Prospector mission scientists -- W. C. Feldman and
colleagues from Los Alamos National Laboratory, S. Maurice from the
Observatoire Midi-Pyrenees in Toulouse, France, and Alan Binder from the
Lunar Research Institute in Gilroy, Calif. -- is that Eshleman and Parks'
suggestions "are worthy of more extended quantitative analysis." The
Prospector researchers defend their position by asserting that the
hydroxyl ions that they measure must be coming from something. The levels
that they have detected are extremely high and are concentrated in two
southern polar craters that are in continuous shadow, making water ice a
likely source. They also say that the amount of water ice that they expect
to find is too small to detect by radar unless it takes the
form of pure ice.

So, regardless of what happens when Prospector crashes, it is unlikely to
resolve the question of whether there are potentially valuable caches of
water ice hidden in perpetual shadow near the moon's pole.

NASA Space Science News for July 27, 1999

Web Site Announcement: LunarImpact.com is a new Science@NASA site devoted to
the end of the Lunar Prospector mission. It includes science news, images
and animations, and tips for amateur astronomers wishing to observe
the spacecraft's scheduled crash into the Moon on July, 31.

Note: readers who photograph tonight's partial lunar eclipse are invited
to send their images to Tony Phillips (as an email attachment to
phillips@spacesciences.com) on Wednesday morning for possible inclusion
in a headline updating the post-eclipse status of Lunar Prospector. Thanks!

Bracing for impact - Professional and amateur astronomers are preparing
to observe the Moon on July 31st when Lunar Prospector plunges into a
permanently shadowed crater in search of water. This story explains
what scientists expect to happen when the spacecraft hits the Moon
and how amateurs might be able to observe the impact.

AAVSO News Flash No. 472

IMPACT OF THE LUNAR PROSPECTOR

We have received the following request from Dr. Tony Phillips, astronomer
and science writer with the NASA Space Science News web site
(http://science.nasa.gov) at NASA Marshall Space Flight Center, for
observations of the impact of the Lunar Prospector on Saturday, July 31,
09:51 UT:

Scientists involved with the Lunar Prospector crash into
the Moon are encouraging amateurs to observe the impact
this Saturday morning, July 31 at 0951 UTC. Most
professional astronomers will be using large telescopes
with sensitive spectrometers to look for a tenuous cloud
of water vapor. The vapor cloud will be invisible through
typical amateur telescopes. However, amateur astronomers
can contribute by watching for a impact plume that may be
visible for up to several minutes after impact.
Theoretical calculations suggest that the plume will
likely be very dim and probably impossible to see so near
to the sunlit edge of the full moon. Nevertheless there
are many uncertainties in the physical models so
scientists are urging amateurs to monitor the impact.
Telescopes equipped with low-light astro-video recorders
are considered best for scientifically useful
observations, but still cameras and simple visual
observations are also valuable. Details and observing tips
for amateurs may be found at
philips@spacesciences.com FAX:
760-872-1382) who will forward them to the appropriate
scientists at NASA/Ames and the University of Texas at
Austin. We would particularly appreciate digital images
and video sent to Tony Phillips as email attachments as
soon as possible after the July 31st collision for posting
on LunarImpact.com.

NASA Space Science News for June 3, 1999

Is Lunar Prospector destined for a Watery Grave? - NASA's first
mission to the Moon in 25 years could end with a splash on July
31, 1999, when ground controllers deliberately crash the
Lunar Prospector spacecraft into a south polar crater in search of
elusive lunar water.

NASA Ames Research Center
Moffett Field, CA

June 2, 1999

LUNAR PROSPECTOR SET TO MAKE SCIENCE "SPLASH"

The mission of NASA's Lunar Prospector will end on July 31, 1999, when
ground controllers attempt to direct the spacecraft to impact the surface of
the Moon inside a permanently shadowed crater near the lunar south pole.

This effort to gain additional science data about the Moon's composition was
proposed to NASA by an external team of scientists led by Dr. David
Goldstein of the University of Texas in Austin. Although the Lunar
Prospector spacecraft will weigh only 354 pounds (161 kilograms) at mission
end, the energy at impact will be the equivalent of crashing a two-ton car
at more than 1,100 miles per hour.

Scientists hope that the direct impact into a lunar crater will liberate up
to 40 pounds of water vapor that may be detectable from ground- and
space-based observatories. A positive detection of water vapor or its
byproduct, OH, would provide definitive proof of what some scientists have
long suspected -- the presence of water ice in the lunar polar regions.

"While the probability of success for such a bold undertaking is low, the
potential science payoff is tremendous," said Dr. Guenter Riegler, Director
of the Research Program Management Division in the Office of Space Science
at NASA Headquarters, Washington, DC.

"External peer reviews of this plan have been very favorable, and we have
concluded that it is both technically and operationally feasible," Riegler
said. "Since the implementation costs are minimal and the mission is
scheduled to end anyway, it seems fitting to give Lunar Prospector the
chance to provide scientific data right up to the very end of its highly
successful mission."

Lunar Prospector was launched on Jan. 6, 1998, with a one-year primary and
six-month extended mission to explore the lunar surface remotely. In March
1998, mission scientists announced that science instruments aboard Lunar
Prospector had detected sufficiently large quantities of hydrogen at the
lunar poles to infer the presence of water ice. In September, scientists
estimated that up to six billion metric tons of water ice may be buried in
the permanently shadowed craters of the Moon's poles.

The current plan calls for a controlled impact of the Lunar Prospector
spacecraft in the early morning hours of July 31 directly into the Mawson
crater, located at the southern lunar pole. This crater is ideal for the
proposed experiment. It is only 31 to 38 miles (50 to 60 kilometers) across
and has a rim which is high enough to provide a permanent shadow, yet it is
low enough to provide for a suitable spacecraft impact trajectory. Data from
other observations suggest that the crater could contain a high
concentration of water ice. Finally, the crater is observable at impact time
from Earth-based observatories and orbiting platforms.

"A positive spectral detection of water vapor or its photo-dissociated
byproduct, OH, would provide definite proof of the presence of water ice in
the lunar regolith," Goldstein said. However, scientists warn that the
failure to observe the desired signal does not mean that water ice is not
present. The model could be wrong, the spacecraft may not impact the desired
region or the impact energy may be insufficient to liberate an observable
plume of water vapor or OH. The overall probability of success is estimated
to be about 10 percent.

Observing time has been granted at the University of Texas McDonald
Observatory and on the Hubble Space Telescope. It is also being sought at
other sites from which the Moon is clearly visible in the early morning
hours of July 31.

Goldstein and his team will present a detailed description of their proposal
in the June 15 issue of "Geophysical Research Letters."

Further information about Lunar Prospector can be obtained at the project
website.

Lunar Prospector was the first of NASA's Discovery class of "faster, better,
cheaper" space exploration missions. The $63 million mission is managed by
NASA Ames Research Center, Moffett Field, CA.

University of Texas, Austin College of Engineering
Austin, Texas 78713-7509

June 1, 1999

UT Austin researchers and NASA to crash spacecraft to find lunar ice

AUSTIN, Texas -- Is there water on the moon? Researchers at The University
of Texas at Austin have designed a quick experiment to find out -- crash a
retired lunar module into the moon's south pole, which is believed to contain
ice.

UT engineers and an astronomer are teaming up with researchers from
NASA-Ames and the Los Alamos National Laboratory to analyze the debris
created by the crash and check for evidence of water.

"The discovery of ice on the moon would be of great importance for human
exploration of space. Space explorers could separate the ice into hydrogen
and oxygen and use it for rocket fuel. They could use the liquid water to
build and supply a lunar base," reasons Professor David Goldstein, a UT
Austin aerospace engineer who helped design the experiment, along with
Professor Steve Nerem, also a UT Austin aerospace engineer.

Goldstein identified a NASA spacecraft now orbiting the moon called "Lunar
Prospector," whose mission will end this summer when it runs out of fuel
and crashes into the moon.

His group has proposed to make Prospector's end a controlled crash, targeting
a crater at the moon's south pole believed to have ice patches. Using some of
the world's most powerful telescopes, Goldstein's group can measure the
plume of water vapor created by the crash, thereby proving water's existence
on the moon. The crash is planned July 31.

Prospector, as part of its primary mission, clearly detected hydrogen at the
moon's poles. Hydrogen, along with oxygen, make up water, so Prospector
found strong, but inconclusive, evidence of water at the poles. Prospector
found the hydrogen inside permanently shadowed craters, craters whose
floors never see direct sunlight, which would melt any ice.

"It really is a long-shot experiment," admits Goldstein. "We are crashing
Prospector into a permanently shadowed polar crater, which means we
cannot see the crash. But we hope to create a barely measurable plume of
debris containing ice crystals, dust and water vapor, which will rise out
of the crater for a few minutes. In addition, although the moon generally
has no atmosphere, we hope the vapor produced by the crash may produce
a very thin atmosphere that we can detect several hours later."

Goldstein's group is coordinating observations from UT's McDonald
Observatory, the Hubble Space Telescope and the Keck Observatory in
Hawaii. NASA has provided preliminary approval for the project, although
final approval is pending.

Goldstein's plan "Impacting Lunar Prospector in a Cold Trap to Detect Water
Ice" is to be published in a forthcoming issue of the Geophysical Research
Letters and presented at the American Geophysical Union's spring conference
June 1-4 in Boston.

Lunar Prospector to gather data closer to moon's surface

On Dec. 19, mission controllers at NASA's Ames Research
Center, Moffett Field, CA, will command the Lunar Prospector
spacecraft into a 40-kilometer (approximately 25-mile) lunar
polar orbit, down from its current 100 kilometer (63 mile)
mapping orbit, signaling the transition to the spacecraft's
extended mission.

The spacecraft will remain in the new 40-kilometer orbit for
about four weeks, and will then be commanded to an even
closer 25-30 kilometer (approximately 15 to 19 mile) orbital
path in January 1999. These actions will officially complete
the end of the very successful primary mission, which began
in January 1998.

The extended mission is expected to continue through June
1999, during which time the five instruments onboard will
gather additional science data at significantly higher
resolutions. These higher resolutions will enable scientists
to continue to refine their estimates concerning the
concentration and form of hydrogen detected at the north and
south lunar poles, which mission scientists interpret as
deposits of water ice. Mapping of the Moon's magnetic and
gravity fields will also benefit greatly from the lower
orbit. Additionally, initial global maps of the Moon's
elements will be confirmed with the close-up data.

BACK TO THE MOON!

Lunar Prospector successfully launched on January 6, 1998 at 02:29 UT.
Launch took place from Launch Complex 46 (LC-46) at Cape Canaveral Air
Station (CCAS), Florida, after a delay of one day. This Sunday, Lunar
Propector will reach his polar orbit around the Moon. The spacecraft
will then start prospecting the lunar surface at an altitude of approximately 63 miles
(100 km) during a one-year mission.

Ames Research Center

Lunar Prospector Mission Status Report

January 7, 1998 12:30 a.m. EST (9:30 p.m. PST, Jan. 6)

NASA's Discovery program of low-cost, science-focused space exploration
missions got a major boost Tuesday evening with the successful launch of
Lunar Prospector. At the current time, all spacecraft systems are
operational and Lunar Prospector is on its way to the Moon.

The compact spacecraft, atop a Lockheed Martin Athena II launch vehicle,
roared off Spaceport Florida's pad 46 at the new, commercial launch
complex at Cape Canaveral, FL, on schedule at 9:28:44 p.m. EST (6:28:44
p.m. PST), less than one second into the opening of today's launch
window.

The launch vehicle's three stages worked as planned, rocketing the craft
to an altitude of 62,500 feet after 88 seconds at Stage 1 burnout. All
additional milestones were achieved on schedule during the remainder of
the ascent phase, culminating in attainment of a successful "parking
orbit" around the Earth at an altitude of 125 statute miles.

After completing almost three-quarters of a revolution around the Earth,
the vehicle's Trans Lunar Injection (TLI) stage completed a successful
64 second burn, blasting the small spacecraft out of Earth orbit and
setting the spin-stabilized vehicle on its 105 hour "coasting" mission
to the Moon.

Telemetry and tracking data were acquired on schedule at launch (T) plus
6 minutes and 20 seconds at Antigua, at T + 20 minutes and 23 seconds at
Ascension, and at T + 51 minutes and 40 seconds at Australia. Deep
Space Network data acquisition at Goldstone, CA occurred at T + 1 hour
and 18 minutes, as scheduled. Payload separation from the third stage
of the launch vehicle was successful completed at T + 55 minutes and 15
seconds. Spacecraft turn-on was accomplished 56 minutes and 30 seconds
after launch.

Lunar Prospector will conduct a one-year primary mission, mapping the
surface composition and internal structure, volatile activity, and
magnetic and gravity fields of the Moon from an altitude of
approximately 63 miles. Additional mapping at altitudes as low as 6
miles above the lunar surface is planned over the following 6 months.
Lunar Prospector is expected to provide definitive evidence of the
presence or absence of water ice in the shaded lunar polar regions.

The Lunar Prospector spacecraft was built for NASA by Lockheed Martin
Missiles and Space, Sunnyvale, CA. The Athena II launch vehicle was
provided by Lockheed Martin Astronautics, Denver, CO. Science
instruments and other important contributions were provided by the Los
Alamos National Laboratory, the U.C. Berkeley Space Science Laboratory,
the University of Arizona, Tucson, AZ, and NASA's Goddard Space Flight
Center, Greenbelt, MD and Jet Propulsion Laboratory, Pasadena, CA. Alan
Binder of the Lunar Research Institute, Gilroy, CA is the Principal
Investigator. The Lunar Prospector mission manager is Scott Hubbard of
NASA's Ames Research Center, Moffett Field, CA.

Los Alamos National Laboratory
Los Alamos, New Mexico

LOS ALAMOS INSTRUMENTS TO PROSPECT FOR WATER ON THE MOON

LOS ALAMOS, N.M., Dec. 30, 1997 -- Sometime in the next month or so,
Los Alamos National Laboratory scientists will gather information bearing
on a major question impacting the future of space colonization: does the
moon have water?

Three Los Alamos instruments on the National Aeronautics and Space
Administration's Lunar Prospector, scheduled for a Jan. 5, 1998, launch,
will look for water, map the location of valuable elements and gather data
on events that release gases from below the surface of Earth's nearest
neighbor.

"If we can find sufficient water, it's going to be a land rush like the
Oklahoma Sooners," said Bill Feldman, project leader for the Los Alamos
instrument package. Los Alamos is a Department of Energy laboratory.

Feldman is confident that Los Alamos' neutron spectrometer will find water
if it is there -- even if it occurs in a very small amount -- most likely in
the form of dirty ice in permanently shaded craters near the moon's poles.
The instrument, which detects and distinguishes neutrons of different
energies, should find even faint traces of any ice that is within three feet
of the lunar surface.

Ever since last year, when radar mapping instruments on the Clementine
probe suggested the possible presence of water on the moon, the
importance of Lunar Prospector has grown. Ice, likely deposited by comet
and meteoroid impacts, would open the way to interplanetary colonization.

"Water is the key resource that will support life as well as travel from the
moon to the planets. Besides sustaining life for moon colonies, hydrogen
from the ice can be extracted for rocket fuel," Feldman said.

"I am sure that there are people who would colonize the moon once
sufficient water is available," he continued. "The moon is one of the best
environments you could possibly have for any number of scientific and
commercial enterprises."

In addition to serving as a fueling station for interplanetary travel, a moon
colony could provide a base for important research in radio, ultraviolet
and infrared astronomy.

Lunar Prospector will take four and one-half days to reach the moon, but
Los Alamos scientists will turn on their three instruments -- the neutron
spectrometer, an alpha particle detector and a gamma ray spectrometer --
90 minutes after launch. They want to calibrate the sensors in transit to the
moon and make sure everything is working perfectly when the spacecraft
reaches its polar orbit around the moon.

After three high-altitude orbital maneuvers at the moon and about a week
after launch, Lunar Prospector will settle into its mapping orbit, skimming
about 60 miles above the lunar surface.

The neutron spectrometer, the latest in a long line of such instruments
built for Los Alamos' nonproliferation programs for the past 35 years,
detects neutrons that escape into space when cosmic rays strike the
upper layers of the moon's surface.

The spectrometer measures neutrons it encounters in three different
ranges of speed, or energy. Neutrons that strike heavy elements bounce
around like a ping-pong ball without losing much energy, whereas
neutrons bouncing against hydrogen -- the lightest element and a
principal component of water -- give up their energy to the hydrogen
relatively quickly. The detector will see very few medium-energy neutrons
in an area with hydrogen, because the high-energy neutrons generated
by cosmic rays quickly become lower energy neutrons. If the detector
sees few or no medium-energy neutrons, water must be present.

Feldman said the instrument could give indications of water within a few
days of beginning its mapping work, if a lot of water is present, or it could
take weeks to make a determination.

"If it's a small spot of ice in a large field of view, it will produce only a
small dip in the data," he explained. "That will take a lot of tweaking
and a lot of interpretation, and I'll be loath to say anything definite
until we're really sure."

Prospector also will carry a Los Alamos gamma ray spectrometer
experiment that will provide global maps of the major rock-forming
elements on the lunar surface. The instrument records the spectrum of
gamma rays and neutrons emitted by elements contained in the moon's
crust. The map of certain elements will provide clues to lunar evolution,
and tell future lunar '49ers where to look for such valuable elements as
aluminum, iron, uranium and titanium.

The moon was sampled during Apollo missions 25 years ago, but along
a near-equatorial orbit that covered only 20 percent of the moon. Lunar
Prosepctor will map the elements over the remainder of the moon's
surface.

An alpha particle spectrometer from Los Alamos will give scientists more
information about the moon's minor -- by Earth standards -- seismic
activity. Lunar magma that cooled just beneath the outer crust contains
uranium, and as uranium-238 decays it produces radon. If moonquakes
vent radon to the surface, the spectrometer will capture the evidence by
recording the alpha particle signatures of radon's radioactive decay.

The three spectrometers were tested for a year and integrated with Lunar
Prospector by Lockheed Martin, which built the spacecraft. The mission
is scheduled to last one year.

Lunar Prospector is part of NASA's Discovery Mission series. Alan Binder
of Lockheed-Martin Missile and Space Corporation is the principal
investigator. Southwest Research Institute in Texas provided electronics
for the Los Alamos instruments. Los Alamos staff members Bruce
Barraclough and Dick Belian are scientific collaborators on the project
and Ken Fuller of Los Alamos' Space Engineering Group was the
principal engineer.

Los Alamos National Laboratory is operated by the University of California
for the U.S. Department of Energy.

University of California-Berkeley

January 5, 1998

Lunar Prospector mission could answer
puzzles about the moon's magnetic field

By Robert Sanders

BERKELEY -- Today's launch of the first NASA moon mission in 25
years -- the Lunar Prospector -- will carry into lunar orbit a UC
Berkeley experiment to measure the patchwork of weak magnetic
fields on the moon's surface.

The moon lacks a strong magnetic field like the Earth's, but
exhibits a much weaker surface field that varies from place to
place, from 100 to 10,000 times fainter than Earth's field. UC
Berkeley astrophysicists hope that a complete mapping of the
faint fields on the surface -- last attempted 25 years ago by
Apollo 15 and 16 -- will reveal the history of the lunar surface,
including whether it once had a global magnetic field like the
Earth.

"The moon may well have had a global magnetic field 3.8 billion
years ago, but that died away," said Robert Lin, a professor of
physics at UC Berkeley and one of the principal investigators for
the magnetic mapping project. "These magnetic anomalies may be
left over from that period, yielding information about that
primordial era.

"We hope that by mapping the magnetic field of the entire moon
and comparing that with surface features and the results of other
mapping onboard Lunar Prospector, we can solve this puzzle and
find out what the old field was."

Lin and project engineer David Curtis at UC Berkeley's Space
Sciences Laboratory built the instrument, called an electron
reflectometer, that will fly aboard Lunar Prospector.

Prospector, scheduled for launch from Cape Canaveral at 8:31 p.m.
EST today (Jan. 5), is one of NASA's much-touted "faster, better,
cheaper" missions, and the third to be launched in its Discovery
Program. Its predecessors were the recent successful Mars
Pathfinder mission and the Near Earth Asteroid Rendezvous (NEAR)
mission launched in 1996. Prospector is a joint project of NASA
Ames Research Center and Lockheed Martin Missiles and Space.

The faint magnetic field on the moon's surface was first detected
by magnetometers placed by Apollo astronauts on the surface, and
then remotely mapped by a UC Berkeley experiment aboard Apollo 15
in 1971 and Apollo 16 in 1972, using instruments built by Lin and
now professor emeritus of physics Kinsey Anderson. Those
instruments obtained only a crude measurement of the fields, and
over only about 10 percent of the lunar surface, in a band around
the equator.

Now, 25 years later, Lin and Anderson are collaborating again to
send an updated instrument aboard Lunar Prospector to map the
entire surface of the moon with ten times the resolution, down to
20-30 kilometers (12-20 miles). A complete map of the surface
should be complete within about six months, Lin said, at which
point the instrument will remap in even greater detail the areas
of high magnetic field, down to a few kilometers resolution -- a
scale of about a mile.

The origin of the faint fields is a mystery, though last November
similar but somewhat stronger surface fields were detected on the
planet Mars by Mars Global Surveyor, by an instrument also built
by Lin and Curtis in collaboration with Goddard Space Flight
Center and Centre d'Etude Spatiale des Rayonnements, Toulouse.

Some lunar magnetic hot spots, such as a strip called Rima
Sirsalis, may date from about 3.8 billion years ago, a time when
the moon may have had a global magnetic field as large as that of
the Earth today.

Other hot spots may carry hints of the moon's past magnetic
field. They may have been created when asteroids struck the
surface, melted, and during cooling captured the magnetic field
at the site of impact.

Still others may be the result of more recent asteroid or comet
impacts. One puzzling finding from the earlier mappings by the
Apollo subsatellites was that regions of high magnetic field seem
to be exactly opposite large impact craters, that is, on the side
of the moon directly opposite a large impact crater. New
information from Lunar Prospector will show whether that was a
coincidence or not, and may suggest an explanation.

Two other areas of strong magnetic field seem to be associated
with a surface feature called an albedo swirl -- a swirled region
of contrasting light and dark, reminiscent of cream stirred into
coffee. More detailed mapping will show whether this too is mere
coincidence or a real association, perhaps caused by a
juxtaposition of irregular magnetic fields.

Magnetic field information also could provide constraints on the
physical processes undergone by the moon in its evolution, such
as how the core formed, the thermal evolution of the crust,
tectonic processes and erosion.

The electron reflectometer is one of five scientific instruments
aboard Lunar Prospector, which will fly in a polar orbit at an
altitude of about 100 kilometers (63 miles) above the surface.
Three of these -- a neutron spectrometer, a gamma ray
spectrometer and an alpha particle spectrometer -- are designed
to "prospect" for minerals, water ice and gases on the lunar
surface. In particular, the neutron spectrometer will seek to
confirm the detection of ice in craters at the poles, as reported
earlier based on radar measurements by the Defense Department's
Clementine probe during a lunar fly-by in 1994.

A combined magnetometer/electron reflectometer will measure the
moon's magnetic field above the surface and at the surface,
respectively. Finally, a Doppler gravity experiment will provide
the best measurements to date of the moon's gravitational field,
allowing future moon missions to use fuel more efficiently.

The electron reflectometer, which measures the energy and
incoming direction of electrons, is a very sensitive detector of
surface magnetic fields, as serendipitously discovered by Lin and
Anderson during the Apollo 15 and 16 missions to the moon. While
flying identical instruments on these two missions, originally
designed to look at charged particles around the moon, they found
that many electrons were coming from the surface.

It turned out that these were being reflected by surface magnetic
fields acting as magnetic mirrors. Charged electrons from the
solar wind corkscrew around the magnetic fields as they approach
the surface, and as the magnetic field increases they spiral
tighter and tighter until, if the field is strong enough or the
angle of approach shallow enough, they reverse direction and
corkscrew back into space.

These electrons are measured by the reflectometer, which looks in
all directions as the satellite rotates through one revolution.

"By looking at the number and angle at which they come in, we get
a measure of the strength of the magnetic field at the surface,"
Lin said.

The data is shipped directly via the Internet from NASA Ames
Research Center, which controls the satellite, to UC Berkeley for
analysis.

Prospector will be launched by an inexpensive Lockheed Martin
launch vehicle, Athena II, taking its maiden voyage. A
three-stage rocket, it will put the satellite in a parking orbit
around Earth while its systems are deployed and checked. After
all systems are go, the satellite will be kicked into a lunar
orbit. The electron reflectometer and related magnetometer --
provided by Goddard Space Flight Center to measure magnetic
fields at the position of the satellite -- will be deployed on
one of three booms projecting from the body of the spacecraft.

LUNAR PROSPECTOR SPACECRAFT CONSTRUCTION COMPLETE

Construction and assembly of NASA's Lunar Prospector spacecraft,
designed to obtain the first complete compositional
and gravity maps of the Moon, has been completed in preparation
for its scheduled September 1997 launch.

Functional and environmental spacecraft tests will be
conducted over the next several months, according to project
manager Tom Dougherty of Lockheed Martin Missiles & Space,
Sunnyvale, CA. Once this activity is successfully completed,
current plans call for the spacecraft to be shipped to Spaceport
Florida in late August for launch on September 24, 1997.

"We're delighted with progress to date," said Scott Hubbard,
NASA Lunar Prospector mission manager at Ames Research Center,
Mountain View, CA. "Lockheed Martin and its construction team put
a detailed program into place and executed it well within the
established schedule and with tight cost control."

The total cost of the mission to NASA, including launch,
mission operations and data analysis, is $63 million.

Why is NASA going back to the Moon? Despite a high level of
scientific and public interest, particularly during
the Apollo era, major gaps remain in scientific knowledge about Earth's
nearest planetary neighbor, according to project scientists. Over
75 percent of the lunar surface is not mapped in detail, and
important questions about the Moon's history, composition and
internal processes remain unanswered.

During its planned one-year polar orbiting mission, Lunar
Prospector will map the Moon's surface composition, gravity and
magnetic fields, and try to detect volatile release activity.
This information should provide insights into the origin and
evolution of the Moon. Lunar Prospector also should directly
determine the existence or absence of water ice in the
Moon's polar regions, which has been suggested by analysis of indirect,
radar-based data from the Clementine mission.

As the first peer-reviewed, competitively selected mission in
NASA's "faster, better, cheaper" Discovery Program series, Lunar
Prospector is an embodiment of the Agency's new way of doing
business. With an emphasis on minimized risk, lowered costs, and
rapid turnaround time, and its prime focus on delivery of science
data, Lunar Prospector will help usher in a new era of Solar
System exploration missions.

"Lunar Prospector is serving as a pathfinder in many
different ways," said Hubbard. The mission has "already made
history in terms of management style, technical approach, cost
management and focused science. Technical insight rather than
detailed programmatic oversight was used to ensure innovation and
maximum return on investment. The Ames program office paid close
attention to the progress of the project and its schedule, cost
and science return, but provided no detailed specifications. The
Principal Investigator was given the flexibility to implement the
best available approach," he said.

The Lunar Prospector spacecraft is a small, spin-stabilized
vehicle with a fully fueled mass of 660 pounds. It is 4.5 feet
high and 4 feet in diameter, with three 8-foot booms or masts.
Solar cells mounted on its outer surface will provide more than
200 watts of power.

Five scientific instruments are mounted on the booms to
isolate them from the main structure and electronics. A neutron
spectrometer will have the capability to locate as little as one
cup of water in about a cubic yard of lunar soil (regolith). The
discovery of water ice in the lunar polar regions would mean that
water, necessary for life support and a potential source of both
oxygen and hydrogen to produce rocket propellant, could be
available for use by future lunar explorers.

A gamma-ray spectrometer will provide global maps of the
elemental composition of the surface layer of the Moon. Improved
knowledge of the concentrations of such elements as uranium,
thorium, potassium, iron, titanium, oxygen, silicon, aluminum,
magnesium and calcium will aid in understanding the composition
and evolution of the lunar crust.

An alpha particle experiment will provide information on the
level of tectonic and volcanic lunar out-gassing activity. It
will map the locations and frequency of radon gas release events
on the Moon, a body thought to be tectonically and volcanically
dead until Apollo provided evidence that it may still have some
limited activity.

A magnetometer and electron reflectometer will map local
lunar magnetic fields, known to be weak compared to the global
magnetic field of the Earth. This will help determine the origin
of such fields and may provide information on the size and
composition of the lunar core.

The Doppler gravity experiment will provide the first global
gravity map of the Moon, essential for planning follow-on robotic
and human exploration missions. It also will provide data on
density differences in the crust, internal densities and the
nature of the core.

When Lunar Prospector is launched, it will take five days to
reach the Moon, making two midcourse maneuvers, deploying booms,
and collecting calibration data via its science instruments en
route. Once the spacecraft reaches the Moon, it will be put into
a circular, 118-minute, 62-mile altitude, polar-mapping orbit to
begin its mission.

If fuel is available at the end of the one-year nominal
mission, lunar mapping may be extended at altitudes as low as 6.2
miles over areas of special interest. After the fuel needed for
orbital maintenance is depleted, the spacecraft will eventually
impact on the lunar surface.

The Lunar Prospector mission is being implemented for NASA by
Lockheed Martin, Sunnyvale, CA, with important contributions from
Los Alamos National Laboratory, the University of California-
Berkeley Space Science Laboratory, the Goddard Space Flight
Center, Greenbelt, MD, and the Jet Propulsion Laboratory,
Pasadena, CA.